When you run UC Surface, bypass it, then run Studio One 3, the Studio 192 integration in Studio One 3 takes over. Talk back still works, but the I/O routing is no longer controlled by UC. It is controlled by Studio One 3.
Close all. Open UC and enable. Click the arrow tab to the far right to verify your TalkBack Assign. Engage Talkback for any outputs you wish. Then Bypass Mixer in UC. Open Studio One 3. Studio 192 Integration and Studio One 3 will take control of I/O routing. Therefore, if you have audio tracks within Studio One 3 assigned to the varied outputs of the Studio 192, and you engage Talkback on the Studio 192. The Talkback mic should be heard on all previously assigned outputs.
You a pair of headphones and connect them to the various outputs on the back of the Studio 192 to confirm this.
Make sure that you are using the current Studio One 3 release and the current UC Surface release and firmware.